Joseph massolle



.Ll. MASSOLLE ELECTROSTATIC TELEPHONE April Re. 17,25?

Original Filed Aug. 53, 1925 FUL- Reissued Apr. 2, 1929.

UNITED STATES PATENT OFFICE.

JOSEPH MASSOLLE, F BERLIN-WILMERSDORF, GERMANY, ASSIGNOR TO TRI-ERGON A. G., OF ZURICH, SWITZERLAND, A CORPORATION OF SWITZERLAND.

ELECTROSTATIC TELEPHONE,

Original No. 1,582,848, dated April 27, 1926, Serial No. 47,661, filed August 3, 1925. Application for reissue filed February 20,

The electrostatic telephones for transforming alternating electric currents with sound tlltlIiltl'OI'lFtlCzi lnl'O sound waves, as hitherto used, comprise a rigid capacity body and an elastic or resilient diaphragm located in close proximity to the former and consisting of a mica him or the like with a metallic coating thereon. If electric potentials are applied intermediate between the rigid capacity body and the metallic coating, the distance between the diaphragm and the capacity surface of the rigid body will vary according" to the degree of applied potential, due to electrostatic attraction and the movements of the. diaphragm will pro- -duce sound or acoustic vibrations in the surrounding air coupled therewith.

The sound waves should correspond, as regards their curve shape, as nearly as posfzosiblc to the fluctuations of the potential. )bviously any \"lbrating diaphragm has a series of pronounced .resonance notes or tonality and the frequencies corresponding to such resonance notes involve or produce disproportionately wide amplitudes of the diaphragm and overrun considerably all of the other frequencies.

The object of this invention is to have the form of the curve correspond perfectly to the variations of the fluctuations of applied potential and with this object in view the distance between the capacity surface and the diaphragm is made essentially less near the periphery than at the centre so that the t llttlzllltlg'll'l will be influenced by the electrostatic forces with a power gradually increasing in the direction from the centre towards the periphery. 'In this way the diaphragm will be efliciently prevented 40 from swinging in pronounced resonance notes.

Vith the above recited and other objects in view, reference is had to the following specification and to the drawings in which there are exhibited two examples or em-- bodiments of the invention which are in no way intended as a limitation upon the scope of the appended claims asit is to be clearly understood that variations and modifications which properly fall within the scope of said claims may be resorted to when found expedient.

In the accompanying drawings forming a part of this specification Figure 1 is a sec- 1929. Serial No. 341,548.

tional view of one embodiment of the improved electrostatic telephone, and Figure 2 is a similar view showing a second embodiment thereof.

Referring to Figure 1 the diaphragm 1, is peripherally attached to and enclosed in a frame 2. In close proximity to the diaphragm but a small distance apart therefrom, a rigid capacity body 3 of slightly concave, preferably conical, shape is provided and firmly connected with theframe 2 by means of screws or the like, as clearly shown. thin sheetof insulating material, such as nnca, having a conducting 'metallic coating; thereon.

If a constant electrical potential difference is provided intermediate between the capacity surface of the body 3 and the metallic coating of the diaphragm, the latter will be bent inwards, upon talking, from the position of rest, shown in dotted lines at 4, into the position 1 shown in full line. The shape of the capacity body or of the active surface thereof involves that the distance between the capacity surface andthc diaphragm is substantially less near the periphery as at 5, than at a central point thereof, as at 6. Consequently the electrostatic forces are substantially more powerful near the periphery than near the centre of the diaphragm and the capacity surface, so that the diaphragm will be controlled or influenced with increasing intensity from the centre towards the periphery thereof.

The seat formed by the head 7 of a screw provided at the centre of .the body 3, serves the purpose of supporting the diaphragm centrally, in order to produce smaller distances between the diaphragm and the body 3 which are equivalent to or bring about an intensification of sound.

The capacity body 3 is provided with perforations 8 for the purpose of reducing the damping in the narrow space between the diaphragm and the body 3. The damping is chiefly produced by or dependent upon the friction of the air fluctuating on and between the diaphragm 1 and the capacity surface, so that it will be possible to control the aerial friction and reduce the same to any desired degree by adequately dimensioning the perforations 8 or selecting the number and position thereof.

The diaphragm may consist of a ill Referring to Figure 2 showing a modification of the embodiment described with reference to Figure 1, 9 designates the diaphragm having a metallic coating, 10 is the frame in which the diaphragm is peripherally enclosed and 11 is the capacity body. As will be seen in Figure 2 the latter is a flat'or plane body and not of conical shape as in Figure Itgoes withoutsaying, that thediaphragm may be divided into a plurality of portions or sections or may be'composed got several sections adapted to be influenced in the manner hereinbefore explained .andspecifically described with reference to Figures 1 and 2. In case of a diaphragm divided .into or, composed of several sections eachpoint or place where the same are clamped in or otherwise Q,

attached toa frameor the like. will beendowed with the described properties peculin to the peripheral portion of the diaphragm.. I v i What I claim is z I H vf1. An electrostatic ;telephoi1e comprising afrigidicapacity body and-a diaphragm cons meted-therewith constitutinga movable condenser plate, the construction and. .arrange- ,ment of the parts being such thatthe distance between, the said body; and. the said, diaphragm isless at theperiphery than at the 2. An electrostatic Itelephone comprising a rigid-capacity body, a resilient diaphragm constituting a movable condenser plate, and

means for securing said diaphragm in spaced a relation to. said body, said parts being so constructed and arranged as to provide-an .air gap between said body and diaphragm of, a ;width decreasingprogressively from the center of the diaphragm and body towards the peripherythereof.

An electrostaticf telephone-comprising -;a rigid plate constituting a capacity body. a resilient diaphragm constituting a movable condenser plate extending over saidplate, the surface of said plat". adjacent to said diaphragm being plane, means for holding $1. 6 central portion of said diaphragm at a definite distance from said plate,- and means for holding the edgeof saiddiaphragm at alessdistance-from said plate.- v I j 4. An electrostatic telephonexcomprising a rigid plate. constituting a capacity body. aresilient diaphragm extending over said plate, said'plate having a central abutment extending upwardly beyond the adjacent surface thereof, and means for securin said diaphragm with its central portion extending over and contacting said abutment and its edges secured at a less distance from said plate than the distance between the portions of said diaphragm adjacent to said abutment,

and said plate.

5. An electrostatic telephone comprising a rlgid plate constituting a capacity body and a resilient diaphragm constituting a movable condenser plate held in ,face to face relation with said rigid plate-at distances between the same. which vary, the variation in said distances being adaptetlzto overcome pronounced resonance of said, diaphragm when acoustically modulated electrical potentials are, applied'between said rigid and movable plates.

6. An electrostatic telephone comprising a, rigid flat capacity body, a diaphragm connected therewith constituting a movable condenser plate, anda means for adjustably holding the diaphragm a certain distance apart'i'romfthesaid body, the saiddistance gradually increasing from the periphery towards the .centreof the two parts. i

IT, Ali-electrostatic telephone, comprising a rigichplane capacity body, a diaphragm connected'therewith, and a screw in the centre otdhe said body for adjust-ably holding the. d aphragm a certain distance apart from thesaid body, the said distance gradually increasing fromv the periphery of the said diaphragm towards the said screw, substantially as and for the purpose set forth.

. 1:8. electrostatic telephone, comprising a rigid capacity body,a diaphragm C011. nected therewith, constituting a movable condense-r plate, and means forliolding the latter firmly connected with the said body ata arying distanceapart from thesame, .said rigid body having perforations therethrough. i

contacting with opposed portions of the rigid perforated body.

El. :A-n electrostatic telephone. accordin to claim Band having port-ions of the diaphragm 10. An electrostatic telephone according to claim,5 and in which the diaphragm 'comprises ,a thinsheet of highly-flexible material carrying conductive means'and maintained in stretched condition. f

. ,11. An electrostatic telephone according to claim 8 and in which the diaphragm is diyided into a plurality of vibratory sections.

, v 12. An electrostatictelephone according to claim 5 and in which the diaphragm comprises a thin'sheet of highly. flexible insulating material carrying a conductive coating and is maintained in stretched condition with a curvature extending overa substan- ,tial area thereof.

13. An electrostatic telephone according to claim 8 and in which the diaphragm is divided into aplurality of vibratory sections, the edges of each of said sections being maintained in closer relationship to said capacity body than other portions.

14. An electrostatic telephone according to claim 5 in which the rigid plate is provided with numerous perforations distributed over its area.

15. An electrostatic telephone according to claim 5 and in which the surface of the diaphragmfacing the capacity body is maintained stretched in a generally concaved shape.

16. An electrostatic telephone according to claim 8 in which peripheral clamping means for the diaphragm is provided at the periphery of the rigid capacity body.

17. An electrostatic telephone according to claim 5 and in which the surface of the diaphragm facing the capacity body is maintained stretched in a generally concavcd shape, portions of the diaphragm however being curved toward the rigid capacity body during operation of the'devicc.

18. An electrostatic telephone according to claim 5 and in which the surface of the diaphragm facing the capacity body is maintained stretched in a generally concaved shape, the central portion of the capacity body engaging the diaphragm and displacing the same to form the concaved shape.

In testimony whereof, I have signed -my name to this petition.

JOSEPH MASSOLLE. 

